Robot cleaner and method for controlling the same

ABSTRACT

A robot cleaner to perform a cleaning process by changing a traveling pattern according to a cleaning start position and a method for controlling the same are disclosed. The robot cleaner recognizes a current position of the robot cleaner upon receiving the automatic cleaning command. If the automatic cleaning process starts from the charger, the robot cleaner performs the automatic cleaning process using a conventional cleaning method. Otherwise, if the automatic cleaning process starts from the outside of the charger, the robot cleaner changes a traveling pattern, performs the spot cleaning process and then selectively performs the automatic cleaning process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/659,401, filed on Mar. 8, 2010, which is currently pending, andclaims the priority benefit of Korean Patent Application No.10-2009-0042029, filed on May 14, 2009 in the Korean IntellectualProperty Office, the disclosures of which are incorporated herein byreference.

BACKGROUND

1. Field

Embodiments of the present invention relate to a robot cleaner which canchange a traveling pattern thereof to new traveling pattern according toa cleaning start position and carrying out a cleaning process along thechanged pattern, and a method for controlling the robot cleaner.

2. Description of the Related Art

Generally, a robot cleaner moves in a cleaning region without receivinga user's command, and sucks dust or dirty material from the bottom ofthe cleaning region so as to carry out a cleaning process in thecleaning region.

The robot cleaner repeatedly performs a cleaning process while movingalong a predetermined traveling pattern to clean a given region.Representative traveling patterns include a lattice-shaped travelingpattern, a random traveling pattern, or the like. If the automaticcleaning command is received in the robot cleaner, the robot cleanerperforms the cleaning process simultaneously while moving along a giventraveling pattern (e.g., the lattice-shaped traveling pattern or therandom traveling pattern). Generally, if the user wishes to control therobot cleaner to start a cleaning process from the outside of thecharger, this means that the user wishes to remove dust gathered at acurrent position. However, a conventional robot cleaner is able toperform the cleaning process only along one traveling pattern (e.g., thelattice-shaped traveling pattern or the random traveling pattern)regardless of whether the automatic cleaning process starts from theposition of the charger or if the automatic cleaning process starts froma position outside of the charger. Most robot cleaners move from theircurrent positions to other positions, so that they are unable to firstremove dust gathered in their current positions. As a result, the usermust directly control the movement of the robot cleaner.

In order to prevent the above user inconvenience, although theconventional robot cleaner has adopted a spot function forpreferentially cleaning a specific position (i.e., a position outside ofthe charger), most users may not know how to use the spot cleaningfunction or may not frequently use this spot cleaning process.

SUMMARY

Therefore, it is an aspect of the present invention to provide a robotcleaner and a control method thereof, which recognize a current positionof a robot cleaner upon receiving an automatic cleaning command, changea traveling pattern according to a cleaning start position of the robotcleaner, thus selectively performing an automatic cleaning process or aspot cleaning process along the changed traveling pattern.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be apparentfrom the description, or may be learned by practice of the invention.

The foregoing and/or other aspects of the present invention are achievedby providing a method of controlling a robot cleaner includingrecognizing a location of the robot cleaner, determining whether therecognized location of the robot cleaner is outside of a charger, andperforming a spot cleaning process along a predetermined travelingpattern when determined the location of the robot cleaner is outside ofthe charger.

The performing of the spot cleaning process may include allowing therobot cleaner to preferentially clean a predetermined region at whichthe robot is presently located, along the predetermined travelingpattern.

The predetermined traveling pattern may include a square spiraltraveling pattern, a curved spiral traveling pattern, or a zigzagtraveling pattern.

The method may further include selectively performing an automaticcleaning process after performing the spot cleaning process.

The recognizing of the robot cleaner location may include determiningwhether a voltage is detected at a charging terminal of the robotcleaner contacting the charger, and determining that the robot cleaneris located outside of the charger when no voltage is detected at thecharging terminal of the robot cleaner.

The recognizing of the robot cleaner location may include determiningwhether a voltage is detected at a charging terminal of the robotcleaner contacting the charger, and determining that the robot cleaneris located at the charger when the voltage is detected at the chargingterminal.

The method may further include performing an automatic cleaning processaccording to a predetermined cleaning scheme when the robot cleaner islocated at the charger.

The foregoing and/or other aspects of the present invention are achievedby providing a robot cleaner charged by a charger including a sensordetecting a cleaning start position of the cleaner, and a controller todetermine whether the cleaning start position is outside of the charger,and to perform a spot cleaning process along a predetermined travelingpattern when determined the cleaning start position is outside of thecharger.

The controller may clean a predetermined region at which the robot ispresently located, along the predetermined traveling pattern.

The controller may perform the spot cleaning process to clean apredetermined region at which the robot cleaner is presently located,and may then stop the spot cleaning process after completely cleaningthe predetermined region.

The controller may establish the predetermined region using either thenumber of rotations or a rotation radius of the traveling pattern.

The controller may selectively perform an automatic cleaning processafter performing the spot cleaning process.

The robot cleaner may further include an input unit to input anautomatic cleaning command. The controller may selectively perform thespot cleaning process or the automatic cleaning process according to acleaning start position, upon receiving the automatic cleaning commandfrom the input unit.

The controller may determine whether a voltage is detected at a chargingterminal of the robot cleaner contacting the charger, and may determinethat the robot cleaner is located outside of the charger when no voltageis detected at the charging terminal of the robot cleaner.

The controller may determine whether a voltage is detected at a chargingterminal of the robot cleaner contacting the charger, and may determinethat the robot cleaner is located at the charger when the voltage isdetected at the charging terminal.

The controller may perform an automatic cleaning process using apredetermined cleaning scheme when the robot cleaner is located at thecharger.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the invention will become apparent andmore readily appreciated from the following description of theembodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a perspective view illustrating the appearance of a robotcleaner according to the exemplary embodiments of the present invention;

FIG. 2 is a block diagram illustrating a robot cleaner according to theexemplary embodiments;

FIG. 3 is a flow chart illustrating a method for controlling a robotcleaner according to a first exemplary embodiment;

FIG. 4 is a flow chart illustrating a method for controlling a robotcleaner according to a second exemplary embodiment;

FIG. 5 illustrates a first traveling locus for an automatic cleaningprocess of a robot cleaner according to an exemplary embodiment;

FIG. 6 illustrates a second traveling locus for an automatic cleaningprocess of a robot cleaner according to an exemplary embodiment;

FIG. 7 illustrates a first traveling locus for a spot cleaning processof a robot cleaner according to an exemplary embodiment; and

FIG. 8 illustrates a second traveling locus for a spot cleaning processof a robot cleaner according to an exemplary embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to the embodiments, examples ofwhich are illustrated in the accompanying drawings, wherein likereference numerals refer to the like elements throughout. Theembodiments are described below to explain the present invention byreferring to the figures.

FIG. 1 is a perspective view illustrating the appearance of a robotcleaner according to an exemplary embodiment.

Referring to FIG. 1, a main body 12 forms the appearance of the robotcleaner 10. Drive wheels 14 (i.e. two) to move the robot cleaner 10 arespaced apart from each other by a predetermined distance, and aremounted to a lower part of the main body 12. Two more drive wheels 14are selectively driven by a driver (motor) to drive each drive wheel 14,such that the robot cleaner 10 can move to a desired direction by thedrive wheels 14. Optionally, a plurality of auxiliary wheels (not shown)may be located at the front and rear of the drive wheels 14, such thatthe auxiliary wheels support the main body 12 and facilitate travelingof the robot cleaner 10.

An input unit 100 to enter a moving traveling command or a cleaningcommand of the robot cleaner 10 is installed on the main body 12. Aplurality of obstacle sensors 102 are installed at the circumference ofthe main body 12 so as to detect furniture, office equipment, and anobstacle, such as a wall, in a cleaning region.

FIG. 2 is a block diagram illustrating a robot cleaner according to anexemplary embodiment. Referring to FIG. 2, the robot cleaner includesthe input unit 100, the obstacle sensor 102, a charger sensor 104, atraveling-distance detector 106, a traveling-direction detector 108, acontroller 110, a driver 112, a cleaning unit 114, and a storage unit118.

The input unit 100 includes a plurality of buttons located either at thetop or at a remote-controller (not shown), to receive the movingtraveling command or the cleaning command (automatic cleaning command orpartial cleaning command) of the robot cleaner 10.

The obstacle sensor 102 detects furniture, office equipment, and anobstacle such as a wall in the range of a cleaning region in which therobot cleaner 10 moves. The obstacle sensor 102 transmits ultrasonicwaves to a traveling path of the robot cleaner 10, and receivesultrasonic waves reflected from an obstacle, to detect the presence orabsence of an obstacle in the traveling path and a distance to theobstacle. In this case, the obstacle sensor 102 includes a plurality ofinfrared light emitting elements and a plurality of infrared lightreceiving elements, to emit infrared rays and receive the reflectedinfrared rays. For example, the obstacle sensor 120 may be formed of aninfrared sensor.

In order to determine whether the robot cleaner 10 starts an automaticcleaning process at the position of a charger 20 (i.e., a dockingstation), the charger sensor 104 detects a voltage of a chargingterminal contacting the charger 20 installed in a cleaning region inwhich the robot cleaner 10 moves, to recognize a current position of therobot cleaner 10. If the voltage is detected at the charging terminal,it is determined that the robot cleaner 10 is located at the charger 20.If no voltage is detected at the charging terminal after the robotcleaner 10 is lifted up at least one time, it is determined that acurrent position of the robot cleaner does not correspond to the charger20. If no voltage is detected at the charging terminal after the movingtraveling command of the robot cleaner 10 is carried out by aremote-controller or the like, it is determined that a current positionof the robot cleaner does not correspond to the charger 20.

The charger 20 is installed in a cleaning region in which the robotcleaner 10 moves, and converts commercial AC power into a power sourcerequired to drive the robot cleaner 10. If the charging terminal of therobot cleaner 10 is brought into contact with the charger 20, the powersource required to drive the robot cleaner 10 is charged in a battery.

The traveling-distance detector 106 detects a traveling distance of therobot cleaner 10, measures the rotation of both drive wheels 14installed for the movement of the robot cleaner 10 using an encoder orthe like, and detects traveling distance information of the robotcleaner 10.

The traveling-direction detector 108 detects a rotation angle of therobot cleaner 10. If an obstacle is detected on a traveling path of therobot cleaner 10, a rotation angle sensor such as a gyro-sensor or anencoder mounted to both wheels 14 is used to detect the rotation angleof the robot cleaner 10 starting from the obstacle.

The controller 110 controls all operations of the robot cleaner 10. Ifan automatic cleaning command is received in the robot cleaner 10, acurrent position of the robot cleaner 10 is recognized by the chargersensor 104, to determine whether an automatic cleaning process startsfrom the location of the charger 20 or from the outside of the charger.If the robot cleaner 10 starts the automatic cleaning process at thelocation of the charger 20, the automatic cleaning process is carriedout according to a conventional cleaning process. If the robot cleaner10 starts the automatic cleaning process at the outside of the charger20, a spot cleaning process is carried out along a traveling pattern(e.g., a curved spiral traveling pattern or a square spiral travelingpattern) established for the spot cleaning process. As a result,although a user does not push a spot cleaning button at aspot-cleaning-desired position, the robot cleaner 10 is controlled tofirst clean a specific position where much dust is gathered.

If the robot cleaner 10 starts the automatic cleaning process at theoutside of the charger 20, the controller 110 controls the robot cleaner10 to first carry out along a traveling pattern established for the spotcleaning process and then carry out the automatic cleaning process usinga conventional cleaning method, or the controller 110 selectivelycontrols the execution of the automatic cleaning process to immediatelycomplete the cleaning process.

If the controller 110 starts the automatic cleaning process at theoutside of the charger 20, it starts the spot cleaning process along atraveling pattern established for the spot cleaning process, and stopsthe spot cleaning process after covering a predetermined area.

The driver 112 drives both driving wheels 14 installed under the mainbody 12 of the robot cleaner on the basis of position informationrecognized by the controller and obstacle information detected by theobstacle sensor 102, such that the robot cleaner 10 automatically movesin a given cleaning region without colliding with a wall or obstacle,and at the same time changes its moving direction to another direction.

Upon receiving a control signal from the controller 110, the cleaningunit 114 drives a suction motor 115 and a brush motor 116 to suck dustor dirty material from the bottom of a cleaning region in which therobot cleaner 10 moves.

The storage unit 118 stores a predetermined traveling pattern dependingon a cleaning start position of the robot cleaner 10, obstacleinformation detected in the traveling process of the robot cleaner 10,and a setup value (e.g., the number of rotations of a pattern suitablefor the spot cleaning, or a rotation radius of the pattern).

The above-mentioned robot cleaner, a control method thereof, andoperation effects will hereinafter be described.

FIG. 3 is a flow chart illustrating a method for controlling a robotcleaner according to an exemplary embodiment.

Referring to FIG. 3, if a user enters a cleaning command (automaticcleaning command or spot cleaning command) of the robot cleaner 10through the input unit 100, the controller 110 receives a cleaningcommand (automatic cleaning command or spot cleaning command) enteredthrough the input unit 100 and determines whether the automatic cleaningcommand is received at operation S200.

At operation S200, upon receiving the automatic cleaning command, thecontroller 110 recognizes a current position of the robot cleaner 10through the charger sensor 104 at operation S202.

A variety of methods may be used to enable the controller 110 torecognize a current position of the robot cleaner 10. For example, it isdetermined whether a voltage is detected at a charging terminalcontacting the charger 20 installed in a cleaning region in which therobot cleaner 10 moves. If the voltage is detected at the chargingterminal, the controller 110 determines that the robot cleaner 10 islocated at the charger 20. Otherwise, if no voltage is detected at thecharging terminal, the controller 110 determines that the robot cleaner10 is located outside of the charger 20.

If the voltage is detected at the charging terminal after the robotcleaner 10 is lifted up by a user at least one time, it is determinedthat the robot cleaner 10 is located at the charger 20. If no voltage isdetected at the charging terminal after the robot cleaner 10 is liftedup at least one time, it is determined that the robot cleaner 10 islocated outside of the charger 20.

Also, the controller 110 detects a manual moving command input to therobot cleaner 10, such that a moving traveling command of the robotcleaner 10 is carried out using a remote-controller or the like. If avoltage is detected at the charging terminal, it is determined that therobot cleaner 10 is located at the charger 20. If no voltage is detectedat the charging terminal, it is determined that the robot cleaner 10 islocated outside of the charger 20.

In order to determine whether the robot cleaner 10 starts from theoutside of the charger 20, the controller 110 determines whether acurrent position of the robot cleaner 10 corresponds to a charger 20 atoperation S204. If it is determined that the current position of therobot cleaner 10 corresponds to the charger 20, the automatic cleaningprocess is carried out using the conventional cleaning method as shownin FIGS. 5 and 6 at operation S206.

The automatic cleaning based on the conventional cleaning method meansthat the robot cleaner 10 drives the suction motor 115 and the brushmotor 116 through the cleaning unit 114 while moving through randomtraveling, pattern traveling (e.g., zigzag traveling) or positionrecognition, such that the robot cleaner 10 sucks dust or dirty materialfrom the bottom of a cleaning region in which the robot cleaner 10moves.

If the robot cleaner 10 is located outside of the charger 20 atoperation S204, the controller 110 controls the robot cleaner 10 to movealong a given traveling pattern appropriate for a spot cleaning process(e.g., a square spiral traveling pattern or a curved spiral travelingpattern) as shown in FIGS. 7 and 8, and drives the suction motor 115 andthe brush motor 116 through the cleaning unit 114, to perform a spotcleaning process to preferentially remove dust gathered in a certainregion where the robot cleaner 10 is presently located at operationS208.

In this case, if spot cleaning is performed on a predetermined regionwhere the robot cleaner 10 is located, the spot cleaning is stopped. Inorder to decide the predetermined region to stop the spot cleaningoperation, the number of rotations or a rotation radius of a squarespiral traveling pattern or curved spiral traveling pattern ispre-established and it is determined whether the spot cleaning iscompletely performed in the predetermined region. In addition, if dustis not detected within a predetermined time while the robot cleaner 10performs the spot cleaning along the square or curved spiral travelingpattern, it is determined that the spot cleaning has been completed, sothat the spot cleaning operation may be stopped.

In the meantime, if the automatic cleaning command is not received atoperation S200, the controller 110 determines whether the spot cleaningcommand is received at operation S210. Upon receiving the spot cleaningcommand, the controller 110 goes to operation S208, controls the robotcleaner 10 to move along the square or curved spiral traveling pattern(See FIG. 7 or 8) appropriate for the spot cleaning process, and drivesthe suction motor 115 and the brush motor 116 through the cleaning unit114, to perform a spot cleaning process to preferentially remove dustgathered in a certain region where the robot cleaner 10 is presentlylocated.

FIG. 4 is a flow chart illustrating a method for controlling a robotcleaner according to another exemplary embodiment.

Referring to FIG. 4, if a user enters a cleaning command (automaticcleaning command or spot cleaning command) of the robot cleaner 10through the input unit 100, the controller 110 receives a cleaningcommand (automatic cleaning command or spot cleaning command) enteredthrough the input unit 100 and determines whether the automatic cleaningcommand is received at operation S300.

At operation S300, upon receiving an automatic cleaning command, thecontroller 110 recognizes a current position of the robot cleaner 10through the charger sensor 104 at operation S302, and determines whetherthe robot cleaner 10 is presently located at the charger 20.

If it is determined that the current position of the robot cleaner 10corresponds to the charger 20 at operation S304, the automatic cleaningprocess is carried out using the conventional cleaning method as shownin FIGS. 5 and 6 at operation S306.

On the other hand, if the robot cleaner 10 is located outside of thecharger 20 at operation S304, the controller 110 controls the robotcleaner 10 to move along a given traveling pattern appropriate for aspot cleaning process (e.g., a square spiral traveling pattern or acurved spiral traveling pattern) as shown in FIGS. 7 and 8, and drivesthe suction motor 115 and the brush motor 116 through the cleaning unit114, to perform a spot cleaning process to preferentially remove dustgathered in a certain region where the robot cleaner 10 is presentlylocated at operation S308, and goes to operation S306 to perform theautomatic cleaning process based on the conventional cleaning method.

The operations to perform the automatic cleaning process based on theconventional cleaning method after performing the spot cleaning processmay be optionally carried out as denoted by a dotted line of FIG. 8.

If the automatic cleaning command is not received at step S300, thecontroller 110 determines whether the spot cleaning command is receivedat operation 310. Upon receiving the spot cleaning command, thecontroller 110 controls the robot cleaner 10 to move along a giventraveling pattern appropriate for a spot cleaning process (e.g., asquare spiral traveling pattern or a curved spiral traveling pattern) asshown in FIGS. 7 and 8, and drives the suction motor 115 and the brushmotor 116 through the cleaning unit 114, to perform a spot cleaningprocess to preferentially remove dust gathered in a certain region wherethe robot cleaner 10 is presently located at operation S312.

Although the embodiments of the present invention have disclosed themethod for allowing the robot cleaner 10 to perform the spot cleaningprocess in a given region where the robot cleaner 10 is presentlylocated using a square spiral traveling pattern or a curved spiraltraveling pattern, the exemplary embodiments of the present inventionare not limited thereto. The same purpose and effects of the embodimentsof the present invention can be achieved even when the robot cleanerperforms the spot cleaning process in a given region where the robotcleaner 10 is presently located along a zigzag traveling pattern havinga predetermined interval (e.g., a narrow interval) corresponding to apredetermined distance.

In addition, although the embodiments of the present invention haveexemplarily disclosed that the spot cleaning process is carried out whenthe user enters the automatic cleaning command of the robot cleaner 10through the input unit 100 and it is determined that the robot cleaner10 is presently located outside of the charger 20, the scope of theembodiments of the present invention is not limited thereto. Even if theuser has not entered an additional cleaning command through the inputunit 100, if the robot cleaner 10 determines that the automatic cleaningprocess is needed, the spot cleaning process or the automatic cleaningprocess may be optionally performed according to a current position ofthe robot cleaner 10.

As is apparent from the above description, the robot cleaner accordingto the embodiment of the present invention recognizes a current positionof the robot cleaner upon receiving the automatic cleaning command. Ifthe automatic cleaning process starts from the charger, the robotcleaner performs the automatic cleaning process using a conventionalcleaning method. Otherwise, if the automatic cleaning process startsfrom the outside of the charger, the robot cleaner changes a travelingpattern, first performs the spot cleaning process and then selectivelyperforms the automatic cleaning process. As a result, although the userdoes not press the spot cleaning button at a spot cleaning position, therobot cleaner can preferentially clean a specific position where muchdust is gathered.

Although a few embodiments have been shown and described, it would beappreciated by those skilled in the art that changes may be made inthese embodiments without departing from the principles and spirit ofthe invention, the scope of which is defined in the claims and theirequivalents.

What is claimed is:
 1. A method of controlling a robot cleaner, themethod comprising: determining whether the robot cleaner is put down ona floor after being lifted up by a user; recognizing, if determined thatthe robot cleaner is put down on the floor after being lifted up by theuser, a cleaning start location of the robot cleaner relative to acharger; determining, by a controller, whether the recognized cleaningstart location of the robot cleaner is at the charger; performing anautomatic cleaning process along a first traveling pattern if it isdetermined that the recognized cleaning start location is at thecharger; and performing a spot cleaning process along a secondtravelling pattern if it is determined that the recognized cleaningstart location is away from the charger.
 2. The method according toclaim 1, wherein the performing of the spot cleaning process includesfirst cleaning a region at which the robot cleaner is presently located,along the second traveling pattern.
 3. The method according to claim 2,wherein the second traveling pattern includes a square spiral travelingpattern, a curved spiral traveling pattern, or a zigzag travelingpattern.
 4. The method according to claim 1, further comprising:selectively performing an automatic cleaning process after performingthe spot cleaning process.
 5. The method according to claim 1, whereinthe recognizing of the robot cleaner location includes: determiningwhether a voltage is detected at a charging terminal of the robotcleaner, the charging terminal being used to charge a battery of therobot cleaner when the charging terminal contacts the charger, anddetermining that the robot cleaner is located away from the charger whenno voltage is detected at the charging terminal.
 6. The method accordingto claim 1, wherein the recognizing of the robot cleaner locationincludes: determining whether a voltage is detected at a chargingterminal of the robot cleaner, the charging terminal being used tocharge a battery of the robot cleaner when the charging terminalcontacts the charger, and determining that the robot cleaner is locatedat the charger when the voltage is detected at the charging terminal. 7.A robot cleaner, comprising: a determination unit to determine whetherthe robot cleaner is put down on a floor after being lifted up by auser; a sensor to detect, if determined that the robot cleaner is putdown on the floor after being lifted up by the user, a cleaning startlocation of the robot cleaner relative to a charger; and a controller todetermine whether the detected cleaning start location is at thecharger, and to perform an automatic cleaning process along a firsttraveling pattern if it is determined that the detected cleaning startlocation is at the charger, and to perform a spot cleaning process alonga second travelling pattern if it is determined that the detectedcleaning start location is away from the charger.
 8. The robot cleaneraccording to claim 7, wherein the controller first cleans apredetermined region at which the robot cleaner is presently located,along the second traveling pattern.
 9. The robot cleaner according toclaim 8, wherein the controller performs the spot cleaning process toclean the predetermined region at which the robot cleaner is presentlylocated, and then stops the spot cleaning process after completelycleaning the predetermined region.
 10. The robot cleaner according toclaim 9, wherein the controller establishes the predetermined regionusing either a number of rotations or a rotation radius of the secondtraveling pattern.
 11. The robot cleaner according to claim 8, whereinthe controller selectively performs the automatic cleaning process afterperforming the spot cleaning process.
 12. The robot cleaner according toclaim 7, wherein the controller selectively performs the spot cleaningprocess or the automatic cleaning process according to the cleaningstart position, upon receiving the command to perform the cleaningprocess from the input unit.
 13. The robot cleaner according to claim 7,wherein the cleaning start location of the robot cleaner is detected bydetermining whether a voltage is detected at a charging terminal of therobot cleaner, the charging terminal being used to charge a battery ofthe robot cleaner when the charging terminal contacts the charger, andthe controller determines that the robot cleaner is located away fromthe charger when no voltage is detected at the charging terminal. 14.The robot cleaner according to claim 7, wherein the cleaning startlocation of the robot cleaner is detected by determining whether avoltage is detected at a charging terminal of the robot cleaner, thecharging terminal being used to charge a battery of the robot cleanerwhen the charging terminal contacts the charger, and the controllerdetermines that the robot cleaner is located at the charger when thevoltage is detected at the charging terminal.